$re = '/(?:\G(?!^)|render\(\')[^\':]*\K:+/m';
$str = 'render(\'MyBundle:Default:index.html.twig\')
or render(\'MyBundle::Default::index.html.twig\')';
$subst = "/";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php